A prior art clutch assembly of the kind as herein referred is described in GB Pat. No. 2,093,133. The planetary forward-reverse gear set and the two friction disk assemblies are thereby arranged on the side of the fixed sheave of the primary pulley of the continuously variable pulley drive in such a manner that the servo cylinder of the servo piston provided for the operation of the adjacently arranged forward friction disk clutch is fixedly connected to the rear side of this fixed sheave. The movable sheave of the primary pulley is on the other side provided with an also rearwardly extending cylindric portion serving as an axial guide of this movable sheave within the axially stationary adjusting cylinder of the hydraulic adjusting means the adjusting piston of which is being supported by a secondary member of the adjusting piston that also axially guides the cylindric portion of the movable sheave. In this known clutch assembly relative large axial and radial dimensions are therefore predominant which receive an even greater enlargement by the provision also of a separate starting clutch means having the form of a hydraulic torque converter as also arranged on the side of the fixed sheave forwardly of the planetary gear set and the two friction disk clutches.
In a similar known clutch assembly as described in U.S. Pat. No. 4,342,238 the planetary gear set and the two friction disk assemblies are arranged on the side of the movable sheave of the primary pulley of the continuously variable pulley drive at a position rearward of its hydraulic adjusting means. The adjusting piston of the hydraulic adjusting means is thereby fixedly connected to the rear side of the movable sheave in such a manner that the axially stationary adjusting cylinder receives an arrangement adjacent to an insert body of the transmission housing which insert body is supported by a hub portion of the pinion carrier of the planetary gear set and is provided with a rearwardly extending cylindric portion serving as the servo cylinder for the servo piston provided for the operation of the adjacently arranged reverse friction disk brake. The servo piston provided for the operation of the forward friction disk clutch is arranged still further rearwardly on the axially outermost position of the planetary gear set axially opposite to the position of the hydraulic adjusting means. This known clutch assembly is therefore also provided with relatively large axial and radial dimensions which thereby as well receive a still greater enlargement by the provision also of a separate starting clutch in the form of a hydraulic torque converter being positioned on the side of the fixed sheave at a forward position of the continuously variable pulley drive.
This invention deals with the object of providing a clutch assembly for a planetary forward-reverse gear set suitable for automotive use which allows smaller axial and radial dimensions of the entire transmission mechanism and whereby the clutch assembly may at the same time be designed in such a manner that the automobile may be started with a sensitive feeling independent of a predetermined horse power of the machine and also independent of a predetermined load condition and a predetermined ground condition.
The invention offers the advantages that by the specific structural combination of the servo means provided for the operation of the forward friction disk clutch and the hydraulic adjusting means provided for the adjustment of the primary pulley of the continuously variable pulley drive the axial dimensions of the entire transmission mechanism may be considerably reduced. This structural combination also allows a simplification of manufacturing and installation of the entire transmission mechanism concurrently with a simplified oil feeding system so that with the aid of a suitable control of the oil feeding system for the servo means of the two friction disk assemblies and the hydraulic adjusting means even the provision of a separate starting clutch in the form of a hydraulic torque converter is no longer necessary.